The present invention relates to a computer system formed by a plurality of computers, and in particular to a method, and system, for allowing a plurality of computer systems to share the same storage device via mutually different interfaces.
In recent years, so-called downsizing is extensively conducted in the field of computer system. The business performed by mainframes in the past has recently been processed by open systems formed by personal computers and work stations.
It is now assumed that a computer is to access a disk device. Traditionally in mainframes, access to the disk device is conducted via an interface standardized so as to transfer a data record of count-key-data record format according to specification of a cylinder number, a header number and a record number (CCHHR). On the other hand, in open systems, access to the disk is conducted via an interface standardized so as to transfer a data block of fixed-sized block data record format according to specification of a logic block address (LBA).
This results in a problem that a disk device generally used in the mainframe cannot be accessed in the open system, and on the contrary, a disk device used in the open system cannot be accessed in the mainframe. Other storage devices such as a magnetic tape device cannot be shared between the mainframe and the open system, either.
Therefore, the user which makes the mainframe and the open system operate in parallel needs to produce individual backups of data respectively in the mainframe and the open system, store the backup data thus produced in separate storage media, and manage them. However, this is a heavy burden on the user's operation. Since the open system is often added to an existing system including a mainframe, it is desirable to be able to backup data of the open system in a magnetic tape device or the like of the mainframe.
In "Data sharing unites mainframes with open systems," David Simpson, Datamation, February 1977, and "Networked storage speeds data access," Tim Quellette, Computerworld, Inc., November 1996, data sharing between mainframes and open systems is proposed, but concrete configurations for realizing it are not disclosed.